Answer :
let the area of the original deck be x * x/6
new deck will have area (x + 4) * (1/6x + 2)
so we can write the equation
(x + 4)((1/6)x + 2) - x^2/6 = 56
x^2/6 + 2x + 2x/3 + 8 - x^2/6 = 56
8x / 3 = 48
x = 144/8 = 18
so length of original deck = 18 feet and width = 3 feet.
new deck will have area (x + 4) * (1/6x + 2)
so we can write the equation
(x + 4)((1/6)x + 2) - x^2/6 = 56
x^2/6 + 2x + 2x/3 + 8 - x^2/6 = 56
8x / 3 = 48
x = 144/8 = 18
so length of original deck = 18 feet and width = 3 feet.